Left Ventricular Systolic Function by Tissue Doppler Imaging and Strain Rate Imaging in Obese Adolescents

Heo, Jong A; Hong, Young Mi

Abstract

PURPOSE
Obesity is a risk factor for cardiovascular morbidity and is frequently associated with coronary artery disease, hypertension, and diabetes mellitus. Conventional Doppler technique is limited by the absence of an adequate apical window to assess the transmitral flow in obese patients. Tissue Doppler imaging(TDI) and strain rate imaging(SRI) were performed to assess the influence of obesity on left ventricular systolic function.
METHODS
In 13 obese and 15 normal adolescents aged 16 to 17 years, height, weight, body mass index(BMI), and obesity index(OI) were measured. Fat mass, body fat percent, and abdominal fat percent were estimated by bioelectrical impedance. Ejection fraction(EF) and myocardial performance index(MPI) were estimated by conventional echocardiography to evaluate left ventricular systolic function. Systolic myocardial velocity and strain rate were estimated by TDI and SRI.
RESULTS
EF(63.8+/-6.4% vs 55.7+/-3.4%) was significantly lower in obese adolescents than normal controls. MPI(0.34+/-0.03 vs 0.48+/-0.06) was significantly higher in obese adolescents than normal controls. Systolic myocardial velocity and strain rate were significantly lower in obese adolescents than normal controls. Strain rate showed a negative correlation with arm circumference(r=-0.558, P<0.05) and BMI(r=-0.332, P<0.05). Strain rate was positively correlated with EF(r=0.557, P<0.05) at the base of left ventricle by SRI
CONCLUSION
Significant decrease in left ventricular systolic function was noted in the moderate degree of obesity. SRI may be a more useful diagnostic tool in evaluating systolic dysfunction in patients with moderate degree of obesity.